diseases of plants

Control

Plant diseases are controlled by methods of cultivation (e.g., crop rotation and the plowing under or burning of crop residue); by application of chemicals, e.g., fertilizers (to correct mineral deficiencies in the soil), spray or dust fungicides, bactericides, and insecticides; by development of disease-resistant strains by genetic methods; by use of alternative species that are not susceptible to the disease; by eradication of diseased plants or of their alternate hosts (e.g., barberries, which harbor wheat-stem rust); and by quarantine measures by state and federal governments to prevent the introduction of foreign plant diseases. Field and orchard crops are more susceptible to destruction than are wild plants, because the close proximity of large numbers of a single species (monoculture) makes possible the rapid spread of disease to epidemic proportions.